Unsupervised linear score normalization revisited

  • Authors:
  • Ilya Markov;Avi Arampatzis;Fabio Crestani

  • Affiliations:
  • University of Lugano, Lugano, Switzerland;Democritus University of Thrace, Xanthi, Greece;University of Lugano, Lugano, Switzerland

  • Venue:
  • SIGIR '12 Proceedings of the 35th international ACM SIGIR conference on Research and development in information retrieval
  • Year:
  • 2012

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Abstract

We give a fresh look into score normalization for merging result-lists, isolating the problem from other components. We focus on three of the simplest, practical, and widely-used linear methods which do not require any training data, i.e. MinMax, Sum, and Z-Score. We provide theoretical arguments on why and when the methods work, and evaluate them experimentally. We find that MinMax is the most robust under many circumstances, and that Sum is - in contrast to previous literature - the worst. Based on the insights gained, we propose another three simple methods which work as good or better than the baselines.